Sensor pixel circuits (sensor pixels) have many applications. For example, when used in pixel arrays as part of a pixel array system for reading out sensed data, such pixel array systems can be used as charge coupled devices (CCDs) for use in digital cameras. Sensor pixels, pixel arrays and pixel array systems also find use in biomolecular and biomedical imaging, chemical sensing and a wide range of other fields.
It is desirable to provide alternative circuits, arrays and systems. It is also desirable to provide alternative methods of operating existing circuits, arrays and systems, and it is desirable to provide methods of operating alternative circuits, arrays and systems.